1. Field of the Invention
The invention is directed to a new process for the production of .beta.-Amino-.alpha.-hydroxy-carboxylic acids and derivatives of the common structure (2R,3S)- or (2S,3R)-N-(X,Y)-3-Amino-2-hydroxy-3-phenyl propionic acid-Z of the formula I ##STR2## wherein X H, (C.sub.1 -C.sub.6) Alkyl, Benzyl,
Y (C.sub.1 -C.sub.6) Alkyl, Benzyl, Formyl, COR.sup.1 or CO.sub.2 R.sup.2, PA0 X,Y together Phthaloyl, Maleinoyl, or Maloneyl (sic), PA0 R.sup.1 (C.sub.1 -C.sub.6) Alkyl, Phenyl, Benzyl, NH.sub.2, 4-NO.sub.2 -Phenyl or 4-NO.sub.2 -Benzyl, PA0 R.sup.2 (C.sub.1 -C.sub.6) Alkyl, Phenyl, Benzyl, 4-NO.sub.2 -Phenyl or 4-NO.sub.2 -Benzyl, PA0 Z H, (C.sub.1 -C5) Alkyl, Phenyl, Benzyl, 4-NO.sub.2 -Benzyl, 4-NO.sub.2 -Phenyl or Allyl PA0 Y (C.sub.1 -C.sub.6) Alkyl, Benzyl, Formyl, COR.sup.1 or CO.sub.2 R.sup.2, PA0 X,Y together Phthaloyl, Maleinoyl, or Maloneyl (sic), PA0 R.sup.1 (C.sub.1 -C.sub.6) Alkyl, Phenyl, Benzyl, NH.sub.2, 4-NO.sub.2 -Phenyl or 4-NO.sub.2 -Benzyl, PA0 R.sup.2 (C.sub.1 -C.sub.6) Alkyl, Phenyl, Benzyl, 4-NO.sub.2 -Phenyl or 4-NO.sub.2 -Benzyl.
2. Discussion of the Prior Art
Compounds of Type I are useful intermediates in the total synthesis of Taxol (Paclitaxel), which finds use in the treatment of different types of cancer. A compound (2R, 3S)-Benzoyl-3-amino-2-hydroxy-3-phenylpropionyl-methylester of Formula II falling under Formula I ##STR3## is for example described in Tetrahedron Letters 35, 2845 (1994) as similarly derived from optically active Phenyl glycine and also as a key step in the enzymatic reduction of an .alpha.-Keto ester. A substantial disadvantage of the synthetic method is that the compound of Formula II can only be isolated in 12% yield. Task of the present invention therefore is to provide a process which delivers higher yields and proceeds in an environmentally friendly and economical manner.